Conventionally, if distortion of an image of a monitoring camera, a camera sensor, and the like is corrected or in order to realize image recognition by a plurality of cameras such as stereo cameras, the camera parameters, which are camera information indicating a focal length and orientation of the camera, and the like, are estimated.
It is conceivable that deviation occurs in the camera parameters when manufacturing the camera and when installing the camera on-site. The camera parameters are changed because distortion occurs in a housing due to pressure in a contact surface when installing the camera or a housing material of the camera is expanded or contracted by temperature, humidity, and the like. In addition, in the camera parameters, errors also occur over a long period of time by vibration and the like. Therefore, in the related art, calibration (correction) of the camera is performed based on estimated camera parameters.
For example, a technique, which obtains data for calibration of a camera by using a plurality of chart photographing images in which optical conditions of the camera photographing a chart for calibration with marks by changing the optical conditions, is described in PTL 1.